Ink jet printers are well known in the art. Generally, an ink jet printer includes an array of nozzles or orifices, a supply of ink, a plurality of ejection elements (typically either expanding vapor bubble elements or piezoelectric transducer elements) corresponding to the array of nozzles and suitable driver electronics for controlling the ejection elements. Typically, the array of nozzles and the ejection elements along with their associated components are referred to as a print head. It is the activation of the ejection elements which causes drops of ink to be expelled from the nozzles. The ink ejected in this manner forms drops which travel along a flight path until they reach a print medium such as a sheet of paper, overhead transparency, envelope or the like. Once they reach the print medium, the drops dry and collectively form a print image. Typically, the ejection elements are selectively activated or energized as relative movement is provided between the print head and the print medium so that a predetermined or desired print image is achieved.
Generally, the array of nozzles, supply of ink, plurality of ejection elements and driver electronics are packaged into an ink jet cartridge. In turn, the printer includes a carriage assembly for detachably mounting the ink jet cartridge thereto. In this manner, a fresh ink jet cartridge may be installed when the ink supply of the current ink cartridge has been consumed. Some ink jet printers provide an indication to the user that the ink supply is running low while others do not. In either case, the printer continues to operate with the result being that the user must recognize when the ink supply is exhausted.
Ink jet printer manufacturers intend for the ink jet cartridges to be disposable. That is, the manufacturers recommend that the cartridges not be reused for a variety of reasons. One reason is that refilling the ink reservoir of the cartridge presents the risk that air will penetrate into the ink supply. Air bubbles in the ink lead to malfunctions of the printer in that the supply of ink to the ejection elements may be interrupted leading to a decrease in print quality as the print head misfires. Another reason is that refilling the ink reservoir of the cartridge presents the risk that an incompatible ink may be introduced into the cartridge. Whether bubble jet or piezoelectric technology is utilized for the ejection elements, the ink formulation is particularly adapted thereto. Furthermore, the ink formulation is also particularly adapted to each manufacturers' print head even if the same type of ejection element technology is used. An incompatible ink placed into the cartridge leads to malfunctions of the printer in that the print head is not designed to work with the incompatible ink. Here again, a decrease in print quality results.
Still another reason for not reusing cartridges which have a bubble jet print head is that the bubble jet print head is designed to be replaced. Bubble jet print heads operate in a caustic environment due to the repeated creation, expansion and contraction of the vapor bubble. Thus, the bubble jet print head only has a limited life. Generally, manufacturers design the print head to last only so long as the ink supply. In this manner, replacing the ink cartridge provides a new supply of ink and a new print head. Thus, replenishing the ink cartridge with ink may lead to a decrease in print quality due to the degradation of the bubble jet print head.
Recently, the postage meter industry and other envelope printing industries have begun to incorporate ink jet printers. A typical postage meter (one example of a postage printing apparatus) applies evidence of postage, commonly referred to as a postal indicia, to an envelope or other mailpiece and accounts for the value of the postage dispensed. As is well known, postage meters include an ascending register, that stores a running total of all postage dispensed by the meter, and a descending register, that holds the remaining amount of postage credited to the meter and that is reduced by the amount of postage dispensed during a transaction. Because U.S. Postal Service regulations require that postage be paid in advance, it had traditionally been required that the user of a postage meter periodically present the meter to a Postal Service employee for recharging. However, more recently it is possible to recharge a meter remotely using telephone communications. At the time of recharging, the user paid to the Postal Service the amount of postage to be credited to the meter and the meter is recharged by increasing the setting of the descending register by the amount paid. The postage meter generally also includes a control sum register which provides a check upon the descending and ascending registers. The control sum register has a running account of the total funds being added into the meter. The control sum register must always correspond with the summed readings of the ascending and descending registers. The control sum register is the total amount of postage ever put into the machine and it is alterable only when adding funds to the meter. In this manner, the dispensing of postal funds may be accurately tracked and recorded.
With the incorporation of ink jet printing, postage printing devices now face the same problems associated with the reuse of ink jet cartridges as are found in general purpose ink jet printers. However, new problems also arise due to the inherent nature of printing an indicia of value. For example, if a general purpose ink jet printer runs out of ink while printing a document, then the user merely installs a new cartridge and reprints the document. On the other hand, if a postage printing device runs out of ink while printing a postal indicia, then the user loses money because the postal funds associated with that postal indicia cannot be recovered. As another example, if some of the ejection elements are not operating due to degradation of the ejection elements from reuse of the cartridge, then the postal indicia will suffer from reduced print quality, even if adequate amounts of ink are present, resulting in a loss of optical character recognition (OCR) readability and loss of sufficient fluorescence necessary to be detected by a facer/canceller apparatus as a valid postal indicia. This will likely result in the mailpiece being returned to the sender by the postal authority. Again, the user loses money because the postal funds associated with that postal indicia cannot be recovered.
Therefore, there is a need for preventing unauthorized reuse of an ink cartridge after an out of ink condition. More particularly, there is a need for a postage printing apparatus including an ink jet printer having an ink jet cartridge wherein the postage printing apparatus disables the ink jet cartridge in response to an out of ink condition. In this manner, the user does not suffer a loss of funds by continuing to operate the postage printing apparatus or by reusing the ink cartridge and suffering a degradation of print quality.